Mount Joel gold prospects, Bronzewing Goldfield (Mount McClure), Leonora Shire, Western Australia, Australiai

Regional Level Types
Mount Joel gold prospects	Group of Prospects
Bronzewing Goldfield (Mount McClure)	Ore Field
Leonora Shire	Shire
Western Australia	State
Australia	Country

Located about 20 km NE of the Bronzewing Mine.

The Mount Joel prospects cover five identified anomalous gold prospects in regolith, along an 8 kilometre, north south trending strike zone. The relief is generally flat, with weathering to a few metres in the north and central parts to 80 metres in the south.

Fresh rock is variably sheared and hydrothermally altered metabasalts and amphibolite. Gold is found in sulphide poor quartz vein stockworks. The gold is usually free, and sometimes visible, associated with concentrations of As, Sb and W.

There are three mineral assemblages at Mt Joel: chloritoid-chlorite-plagioclase-quartz-garnet; chlorite-plagioclase-quartz-garnet; and chlorite-hornblende-plagioclase-quartz-garnet. The variety reflects the range of mineral chemistry and alteration processes effecting the metabasic rocks. The garnets are manganese rich, with up to 25% spessartine content.

The five prospects are named 3000mN, 2400mN, 1600mN, 800 mN, and OmN.

In general they show major variablity in gold concentrations depending on depth. Residual enrichment of gold in the transition zone amounts to 50 to 100%. A relative Au poor zone in the upper oxide areas at 3000mN and 2400mN. A marked interface, most apparent at the 800mN and OmN prospects. Lower grade Au in the transported overburden, except at 0mN, where it is thought gold has been transported in from other Au rich areas. There is a poor correlation between quartz content and gold at the 0mN prospect.

The source goes into great detail describing the regolith which will not be repeated here. Very generally there is a pisolitic and laterite zone and sometimes paleaochannel sediments and clays at the top. Upper levels are often strongly leached and contain kaolin. Below this is a saprolite zone which depending on depth, leaching, the influence of Fe can be bright reddish brown, purple, orange, or yellow. Below this is saprock.

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References